Elon Musk is losing out big time on cheap gas prices

A drop in gas prices usually goes hand in hand with a decline in demand for alternative energy and electric cars.

Elon Musk may have lost about $1 billion due to this simple economic reasoning—he's the biggest shareholder in solar panel installation company SolarCity as well as in electric car company Tesla Motors, where he is CEO. Musk owns more than 28 million Tesla shares and about 21 million SolarCity shares, according to MarketWatch.

In late November when OPEC decided not to cut oil production to bolster crude prices, the value of Musk's holdings of Tesla and SolarCity were around $8.2 billion—now the value is at about $7 billion, reports MarketWatch.